Pinpoint Test Z: The Power Seat Is Inoperative/Does Not Operate Correctly - Third Row Power-Fold, Left Seat
Seats
Pinpoint Tests
Pinpoint Test Z: The Power Seat is Inoperative/Does Not Operate Correctly - Third Row Power-Fold, Left Seat
Refer to Wiring Diagram Set 120, Power Seats for schematic and connector information. Diagrams By Number
Refer to Wiring Diagrams for component testing. Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) enables the system by energizing the power-fold seat relay. When energized, the power-fold seat relay supplies battery voltage to the left third row seat control switch on circuit SBB32 (VT/RD). Ground is supplied to the seat control switch on circuit GD151 (BK/GN). The left third row seat control switch supplies voltage and ground to the left third row power-fold seat motor on circuits CPS49 (BN/GN) and CPS50 (BU/BN) to operate the seats. An additional wire harness is used for extended length vehicles (Expedition EL and Navigator L) to supply voltage and ground to the power-fold seat motors on circuits CPS51 (VT/GY) and CPS52 (YE/GN).
The SJB only enables the system when the transmission selector is in PARK. The SJB disables the system after 10 minutes when the ignition is OFF. The SJB re-enables the system for 10 minutes if any door, liftgate or liftgate glass is opened or by pressing the unlock button on the Remote Keyless Entry (RKE) transmitter.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Left third row seat control switch
- Left third row power-fold seat motor
PINPOINT TEST Z: THE POWER SEAT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY - THIRD ROW POWER-FOLD, LEFT SEAT
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Z1 CHECK FOR VOLTAGE TO THE LEFT THIRD ROW POWER-FOLD SEAT MOTOR
NOTE: Make sure the right seat operates. If both seats are inoperative, GO to Pinpoint Test Y to diagnosis. Pinpoint Test Y: The Power Seat Is Inoperative - Third Row Power-Fold, Left and Right Seats
- Disconnect: Left Third Row Power-Fold Seat Motor C4181.
- Ignition ON.
- Measure the voltage between the following, while operating the left third row seat control switch up and down:
- For Expedition and Navigator, measure the voltage between left third row power-fold seat motor C4181-2, circuit CPS50 (BU/BN), harness side and C4181-1 circuit CPS49 (BN/GN), harness side.
- For Expedition EL and Navigator L, measure the voltage between left third row power-fold seat motor C4181-1 circuit CPS51 (VT/GY), harness side and C4181-2 circuit CPS52 (YE/GN), harness side.
- Is the voltage greater than 10 volts when the switch is operated in both directions and 0 volt in the rest position?
Yes
INSTALL a new left third row power-fold seat motor. REFER to Power-Fold Seat Motor Power-Fold Seat Motor. TEST the system for normal operation.
No
GO to Z2.
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Z2 CHECK FOR VOLTAGE TO THE LEFT THIRD ROW SEAT CONTROL SWITCH
- Disconnect: Left Third Row Seat Control Switch C4179.
- Measure the voltage between left third row seat control switch C4179-2, circuit SBB32 (VT/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z3.
No
REPAIR the circuit. TEST the system for normal operation.
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Z3 CHECK THE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between left third row seat control switch C4179-6, circuit GD151 (BK/GN), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to Z4.
No
REPAIR the circuit. TEST the system for normal operation.
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Z4 CHECK THE POWER-FOLD SEAT MOTOR CIRCUITS FOR AN OPEN
- For Expedition and Navigator, measure the resistance between:
- left third row seat control switch, C4179-1, circuit CPS49 (BN/GN), harness side and left third row power-fold seat motor C4181-1, circuit CPS49 (BN/GN), harness side.
- left third row seat control switch C4179-5, circuit CPS50 (BU/BN), harness side and left third row power-fold seat motor C4181-2, circuit CPS50 (BU/BN), harness side.
- For Expedition EL and Navigator L, measure the resistance between:
- left third row seat control switch, C4179-1, circuit CPS49 (BN/GN), harness side and left third row power-fold seat motor C4181-1, circuit CPS51 (VT/GY), harness side.
- left third row seat control switch C4179-5, circuit CPS50 (BU/BN), harness side and left third row power-fold seat motor C4181-2, circuit CPS52 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new left third row seat control switch. REFER to Seat Control Switch - Third Row Seat Control Switch - Third Row. TEST the system for normal operation.
No
REPAIR the circuit(s). TEST the system for normal operation.
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